This error message can occur on iOS devices if the app was originally purchased by another family member and shared with you via Family Sharing. The first thing to check is to make sure the person who originally downloaded the app still has Family Sharing configured to share the app with you.
Sometimes this error message can appear after an iOS update, in which case you may want to try the following steps:
- Go to your iPhone Settings -> General -> iPhone Storage.
- Scroll down and tap on ev.energy.
- Select Offload App.
- Return to your iPhone home screen and tap on the ev.energy app icon to reinstall the app.
- If that does not work you can also try logging out of the App Store app on your device, and then logging back in.
Finally, if none of those steps resolved the issue, please open a support request directly with Apple's App Store support for further assistance. Since Apple operates the Family Sharing program and we do not have access to it, you will need to contact them to get the issue resolved.
For more information see the external article below: